> ..."this" will be the window object, not an instance of Songlist.
Doh! Sorry, I forgot, it won't be window, it'll be the img element.
I keep forgetting that Prototype's event hooking stuff will default
'this' in the handler to the element on which the event occurred. My
bad, apologies.
--
T.J. Crowder
tj / crowder software / com
On May 18, 2:32 pm, "T.J. Crowder" <[EMAIL PROTECTED]> wrote:
> Hi,
>
> No, that code probably doesn't do what you mean it to do -- your code
> hooking the event:
>
> > img.observe('mouseover', Songlist.mouseover);
>
> ...doesn't preserve "this" (as we discussed in another thread).
> Consequently when this code gets called:
>
> > mouseover: function() {
> > this.src = 'anotherimage.gif';
> > }
>
> ..."this" will be the window object, not an instance of Songlist.
>
> It's really worth stopping coding for a moment and reading up on how
> "this" works in JavaScript. I've pointed you to this blog entry
> before:http://blog.niftysnippets.org/2008/04/you-must-remember-this.html
>
> Additionally, Flanagan's book will pay you back in time savings pretty
> much any time you spend reading
> it:http://www.oreilly.com/catalog/jscript5/http://www.amazon.com/dp/0596101996
>
> In terms of the actual problem with the above code, as with last time,
> you want to use
> bindAsEventListener:http://www.prototypejs.org/api/function/bindAsEventListener
>
> Hope this helps,
> --
> T.J. Crowder
> tj / crowder software / com
> On May 18, 12:31 pm, "[EMAIL PROTECTED]"
>
> <[EMAIL PROTECTED]> wrote:
> > OK, I really tried hard before I posted the above message, but sitting
> > on the toilet I found the mistake.
> > The code must look like that, than it works:
>
> > var Songlist = {
> > initialize: function() {
> > img = document.createElement('img');
> > [...]
> > img.observe('mouseover', Songlist.mouseover);
> > $('body').insert(img);
> > }
> > mouseover: function() {
> > this.src = 'anotherimage.gif';
> > }
>
> > }
>
> > Songlist.initialize();
>
> > On 18 Mai, 13:25, "[EMAIL PROTECTED]"
>
> > <[EMAIL PROTECTED]> wrote:
> > > Hello,
>
> > > I habe a problem with the following code (shortened):
>
> > > var Songlist = {
> > > initialize: function() {
> > > img = document.createElement('img');
> > > [...]
> > > img.observe('mouseover', this.mouseover);
> > > $('body').insert(img);
> > > }
> > > mouseover: function() {
> > > this.src = 'anotherimage.gif';
> > > }
>
> > > }
>
> > > Songlist.initialize();
>
> > > Passing the image with my mouse I always get the error: "handler has
> > > no properties"!
> > > I would be happy if you gave me a tip, where what causes this error!
>
> > > M. Hoffmann
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